I have both a PC (3.0 GHZ, 1gb RAM, 128 ATI) and a Mac (iBook G3 700 for my wife, and most recently a iBook G4 1.2 for myself). I like both platforms a great deal.
My PC blows my iBooks away in terms of speed, responsiveness and my "power needs". I use my PC for some gaming (WoW, Half-Life2), DVD authoring, editing, burning, and some photo editing. I know that my iBook could do photo editing very well, but its hard drive isn't big enough, and I'd really need a G5 to get the speed that I get with my PC. I've found that the superdrives on Macs are rather slow (usually rebadged Sony's = Lite-Ons). I've found it much easier and faster to do DVD stuff on PC
without spending a fortune. Sure, I could go pick up Final Cut Pro and the like, but I've found great software for free on the PC side.
My mood is happier when I use my Mac. Its just easier for me to navigate. Weird things don't happen on my Mac that I can't explain like on my PC. I use my iBook for writing papers, reports, general web browsing, music composition and mp3s, and most of my email. I love the clean look and stability of Mac OSX. I know I'm not pushing my iBooks to there limits in terms of power, but I've never had either crash on me. I also really like how OSX handles multitasking. Expose is absolutely awesome. I miss it when I'm on my PC. I'm also a Garage Band junkie. I'm sure there are similar programs for the PC that I haven't tried, but its the easiest music composition software I've used.
In sum, whenever I'm on my Mac, there are things that I miss about my PC, whenever I'm on my PC there are things I miss on my Mac. You can't beat the PC in terms of availability of software, modification support, and affordability. But I'd argue that you can't beat Macs in terms of stability, functionality of OS (e.g. multitasking), style, and bundled applications. It would be hard for me to give up either platform at this point. I don't think that I'd ever buy a Mac Desktop (other than maybe a Mac Mini) because I think they are a hard sell. But, I think the Apple Laptops are among the best on the market.
If you haven't already checked it out, Anandtech.com has a three part series about a hardcore PC users reactions to a Mac. Very interesting reading!
Section 1
Section 2
Section 3